HI @anon80118353,
As it stands, there is no option to require for all subtasks to be completed before being able to complete the parent task. With that said, this is a popular request in the Forum, so if you haven’t yet, I would recommend upvoting this existing #productfeedback thread we have on the same topic → Mark all subtasks complete before allowing tasks to be marked complete - #38 by Bastien_Siebman